The director, 61, scored a box office hit in 2009 with the release of the original fantasy blockbuster, which starred Sam Worthington and Zoe Saldana.
It currently holds the title as the highest-grossing movie in history, said the Hollywood Reporter.
He then announced there would be three follow-ups, with "Avatar 2" scheduled to hit cinemas in late 2016, but last year, Cameron admitted the writing process was taking longer than expected, and the second instalment was postponed until Christmas, 2017.
Cameron made a surprise appearance at CinemaCon in Las Vegas and offered up both good and bad news to fans.
"I've been working with the top four screenwriters and designers in the world to design the world of Avatar going forward. The environments, new cultures... From what I'm seeing, the art on the wall... In pure imagination is just beyond the first film. I'm speechless."
"Avatar 3" is pegged for release in 2020, with the fourth and fifth instalments following in 2022 and 2023.